# researching the feasability to convert the cnc router to a touchsensor 3D scanner

+

−

Please add additional thoughts on [[Talk:CNC_Router|Talk page]]

+

−

=Found products=

+

We added a LED to the carriage to illuminate the milling area.

−

* [http://www.cnc-sable.nl/sable-2015-p-21.html Sable 2015]

+

−

* [http://www.repairablemachines.com/ MiniCnc, made at TimeLab Gent]

+

== Software ==

+

The CNC router controlled by sending it gcode. The sending of the gcode is done with replicatorG.

+

Multiple programs can be used to generate gcode.

−

=Selection: MiniCnc, made at TimeLab Gent=

+

===ReplicatorG===

−

[[File:Pcb.jpg|top|right|142px|caption]]

+

ReplicatorG will report about a feedrate of zero, this is normal acording to https://groups.google.com/group/ultimaker/browse_thread/thread/6892f2b14d11b361 and is caused by our CNC lacking a feedback mechanism.

+

We are using replicatorG version 25.

+

if starting replicatorG normally it will not be able to control /dev/ttyUSB0 to talk to our CNC. So you either have to start replicatorG as root or run

+

sudo chmod 777 /dev/ttyUSB*

−

*Q: Minimal distance between tracks when milling PCBs?

+

=== Cad.py ===

−

*A: About 0.2 mm

+

Cadpy can transform bitmaps to gcode. Beware that multiple versions of this tool exist, not all of which do work with our machine.

−

*Q: What host software is used to transform CAD designs to G-code?

+

=== Software we haven't checked out yet ===

−

*A: Replicatorg with skeinforge as plugin software and a custom http://www.repairablemachines.com/usingcadpy.html

* [http://www.digitalplayground.be/ website of Kris Wauters who has a lot PCB milling experience]

The last days we've discovered some problems when milling PCB's. The accuracy of the CNC router seems to be pretty good, however it seems that our current milling bits are not suitable to perform the job.

The last days we've discovered some problems when milling PCB's. The accuracy of the CNC router seems to be pretty good, however it seems that our current milling bits are not suitable to perform the job.

Line 61:

Line 67:

The other fine milling bit could not deliver smooth tracks due to sharp edges.

The other fine milling bit could not deliver smooth tracks due to sharp edges.

−

Another problem is the production of fine dust (and noise). It's certainly not healthy to breath in small copper particles so we really need to make an isolated box asap.

+

Milling PCB's produces fine dust. A wooden box was made to prevent breathing in small copper particles.

−

Thanks to the great insights of Kris Wauters I suggest the following todo's:

* Find a better way to fix the PCB's. The best way seems to be using double sided tape, egally applied to the bottom PCB surface. Then the PCB is attached to the flattened (by milling) MDF surface. The tape will help in straighten the PCB surface by pulling it against the MDF surface.

* Make a flat bottom surface. Please notice that 'flat' is relative to the CNC machine & milling spindle (Dremel). So the best way to do this is placing the CNC router on a new MDF panel (18mm minimum) and mill about 1mm of the surface away. Then we are sure that the relative height/depth is the same for each possible coordinate. We need the following:

* Make a flat bottom surface. Please notice that 'flat' is relative to the CNC machine & milling spindle (Dremel). So the best way to do this is placing the CNC router on a new MDF panel (18mm minimum) and mill about 1mm of the surface away. Then we are sure that the relative height/depth is the same for each possible coordinate. We need the following:

** MDF panel (700 x 700 x 18 mm) (or thicker)

** MDF panel (700 x 700 x 18 mm) (or thicker)

** milling bit for MDF, flat top (10 a 20mm milling diameter)

** milling bit for MDF, flat top (10 a 20mm milling diameter)

−

−

* Find a better way to fix the PCB's. The best way seems to be using double sided tape, egally applied to the bottom PCB surface. Then the PCB is attached to the flattened (by milling) MDF surface. The tape will help in straighten the PCB surface by pulling it against the MDF surface.

−

** Buy strong double sided tape (not very thick)

−

−

* Design wooden box to place over the CNC router. The box should not be attached to CNC router itself, but I guess we can put it loosely on the MDF bottom plate. We can use small wooden beams on the bottom plate to assure that the box and the CNC router are always be placed on the same position.

−

** design box

−

** buy MDF plates

−

** buy wood glue

−

** buy wooden beams (10x10 or 15x15 mm)

−

** use plexiglass as lid? ("deksel")

−

** buy screws?

−

−

* design a panel to prevent dust from milling reach into electronics area

−

** measure and design panel (done - Jeff)

−

** create panel (planned - Jeff)

−

−

* use some kind of cleaning device to remove possible toxic dust

−

−

=progress log=

−

−

==29/02/2012==

−

ivom, tomvdz, sorry-forgot-your-name

−

−

*checked and fixed all wiring

−

*first attempt to draw a square

−

*the beast works!

−

−

==07/03/2012==

−

Tomvdz, Jeffrey,Ivom

−

−

*Installed the Dremel

−

*Calibration night:

−

*The square wasn't a square

−

*tweaking parameters in the machines/minicnc_rep25.xml file

−

*calibration done, error deviation is about .2mm

−

−

==14/03/2012==

−

Jeffrey, tomvdz, ivom

−

−

[[File:CNCmachine.jpg|200px|thumb|left|CNC router]]

*accuracy testing on pcb milling

*accuracy testing on pcb milling

Line 124:

Line 89:

-accuracy: very fine to 1mm distance between lines

-accuracy: very fine to 1mm distance between lines

-no rough edges

-no rough edges

−

−

[[File:CNC_PCB1.jpg|200px|thumb|left|test 1]]

Line 133:

Line 96:

-different depths: from 0.2mm to 0.4mm

-different depths: from 0.2mm to 0.4mm

-accuracy: +- 0.25mm, but edges are too rough and unclean

-accuracy: +- 0.25mm, but edges are too rough and unclean

−

−

[[File:CNC_PCB2.jpg|200px|thumb|left|test 2 & 3]]

−

−

[[File:CNC_PCB3.jpg|200px|thumb|left|test 4]]

* used G-code

* used G-code

Line 144:

Line 103:

;G91 ; relative position, no opto-end stops...

;G91 ; relative position, no opto-end stops...

G92 X0 Y0 Z0 ;huidig pos = oorsprong

G92 X0 Y0 Z0 ;huidig pos = oorsprong

−

G00 Z05.000 ;boor omhoog

G00 Z05.000 ;boor omhoog

G1 X10 Y10 F66 ;begin pos 1ste lijn

G1 X10 Y10 F66 ;begin pos 1ste lijn

Line 174:

Line 132:

</syntaxhighlight>

</syntaxhighlight>

−

==21/03/2012==

−

* Build a wooden case

−

* Build a seperator to insulate the electronics from dust

−

* measured the maximal range (X;173mm, Y:179mm)

−

* recalibrated the tension on the belt, the axis weren't true relative to one another

−

* tried to fix the third motor controller above the second one using 'draadstangen'

−

−

==24/03/2012==

−

* mounted the third motor controller using draadstangen

−

* tried to engrave tux in scrap wood, which failed miserably

−

* increased the tension on the belt

−

* while doing the former we adjusted the way the tension bolts are attached

−

* increased the voltage on the Y axis motor

−

* second try at engraving tux, gcode is at http://pastebin.com/g6gK413Y#

−

**got loats of errors about a feedrate of zero, this is normal acording to https://groups.google.com/group/ultimaker/browse_thread/thread/6892f2b14d11b361 becaus of no feedback mechanism

−

**We didn't have enough time to let it mill the whole image, but we still saw that the result was quite accurate, exept for some strange errors. These were error always faded in or out, indicating variance on the Z axis. We suspect that the mill doesn't wait for the drill bit to reach traveling height before moving to another X,Y coordinate.

−

**This is probably caused by errors in the gcode outputted by cad.py (version 16/5/11 kurt)

−

** The error seems to be a missing G01 statement when raising to travel height:

−

<syntaxhighlight lang=g-code>

−

G01 X47.4486 Y61.9125 Z-0.3000

−

Z1.0000

−

G00 X51.6819 Y72.4958 Z1.0000

−

G01 Z-0.3000

−

G01 X52.3875 Y72.4958 Z-0.3000

−

</syntaxhighlight>

−

−

==28/09/2012==

−

* Third attempt at engraving tux in scrap wood, gcode at http://pastebin.com/ee8g8e0T

−

* Gcode was produced by cad.py (16/05/11, kurt) and corrected by the sed line `sed 's/^ Z/G01 Z/'`

* both the gcode and the machine worked fine, leading to satisfying results, however some lesser issues were apparent

−

** the engraving depth was deeper at one side than at the other, which means the base plate is not parralel to the X,Y plane. There seems to be some glue residue on the base plate which we should sand off, and test afterwards if both planes are parralel

−

** paths need to be closer together than 0.5 times the tool width to get an even engraved surface when using a round milling bit to get an even engraved surface (striping was visible

−

* photographs of the last 3 attempts were taken, and should be uploaded soon

−

−

[[File:CNCtux1.jpg|thumb]]

−

[[File:CNCtux2.jpg|thumb]]

−

[[File:CNCtux3.jpg|thumb]]

−

−

==04/04/2012==

−

* started a test run of the VW logo in foam. As the goal is to engrave it 300 mm wide the design was sliced in two. the left part was converted to gcode using cad.py and corrected with sed. We used a 1mm engraving bit. The left part took 94 minutes to engrave (and counting)

−

* we will need real endmills to do any serious work

−

* cad.py doesn't optimize the order in which the paths are engraved, which makes the engraving time a lot longer than it needs to be

−

* I looked into pycam, a tool which looks promissing for milling out 3d objects and 2d engravings: http://sourceforge.net/apps/mediawiki/pycam/index.php?title=Main_Page

−

* Found a nice guide made by a guy who makes robotics components in his garage. He mills out the parts, makes a silicone mold and then casts the parts in PU. Buildlog: http://www.flickr.com/photos/candy-bottoms/sets/72157625850569320/detail/ Guide: http://lcamtuf.coredump.cx/guerrilla_cnc1.shtml and http://lcamtuf.coredump.cx/guerrilla_cnc2.shtml

** Probably the accuracy can be increased with a better spindle (with ball bearing) like the KRESS 800 FME

−

[[File:dremel_runout_pcb.jpg|thumb|dremel runout]]

−

[[File:pcb_new_bit.jpg|thumb|result with new bit]]

−

==19/052012==

+

== Extrusion moulding ==

−

TomVerlinden, Ivom

+

A nice guide made by a guy who makes robotics components in his garage. He mills out the parts, makes a silicone mold and then casts the parts in PU. Buildlog: [http://www.flickr.com/photos/candy-bottoms/sets/72157625850569320/detail/ buildlog], [http://lcamtuf.coredump.cx/guerrilla_cnc1.shtml part 1] and [http://lcamtuf.coredump.cx/guerrilla_cnc2.shtml part 2] of the guide.

−

* Rust!!!! Bot seems defunct, greasing the rods on next installment.

+

==ToDo==

+

* replace the plastic guiding bearings with some better metal bearings. One of the plastic ones has the tendency to stay behind

+

* make .g (the extension for gcode) an accepted extension on the wiki so we can upload it here.

+

* Create an emergency stop button. While there is a stop button in replicatorG, this doesn't immediately stop the CNC, which will first execute some cached instructions.

+

* while the endmill is less than 1mm, it's path seems to be about 2mm to the naked eye. This greatly decreases our accuracy.

Latest revision as of 01:00, 21 December 2013

The goal of this project is to build a CNC router that can mill regular PCBs with non-SMD IC components, MDF, stryrofoam HDPE and nylon. The budget is around 1000 euro.
We ended up going for the MiniCnc, made at TimeLab Gent

the CNC router

The minimal distance between tracks when milling PCBs is about 0.2 mm, according to the people at timelab Ghent.
The maximal range is (X:173mm, Y:179mm).

At the moment the base plate is not parralel to the X,Y plane. There seems to be some glue residue on the base plate which we should sand off.

At the moment the accuracy is limited by the dremel, and the runout on its spindle. This can be seen when milling a point with a small diameter endmill,
instead of a small hole, a tiny circle will be milled. Probably the accuracy can be increased with a better spindle (with ball bearing) like the KRESS 800 FME

We added a LED to the carriage to illuminate the milling area.

Software

The CNC router controlled by sending it gcode. The sending of the gcode is done with replicatorG.
Multiple programs can be used to generate gcode.

ReplicatorG

ReplicatorG will report about a feedrate of zero, this is normal acording to https://groups.google.com/group/ultimaker/browse_thread/thread/6892f2b14d11b361 and is caused by our CNC lacking a feedback mechanism.
We are using replicatorG version 25.
if starting replicatorG normally it will not be able to control /dev/ttyUSB0 to talk to our CNC. So you either have to start replicatorG as root or run

sudo chmod 777 /dev/ttyUSB*

Cad.py

Cadpy can transform bitmaps to gcode. Beware that multiple versions of this tool exist, not all of which do work with our machine.

The last days we've discovered some problems when milling PCB's. The accuracy of the CNC router seems to be pretty good, however it seems that our current milling bits are not suitable to perform the job.
The ball point milling bit gives smooth tracks without sharp edges, but the milling width is heavily influenced when the PCB surface isn't flat.
The other fine milling bit could not deliver smooth tracks due to sharp edges.

Milling PCB's produces fine dust. A wooden box was made to prevent breathing in small copper particles.

Find a better way to fix the PCB's. The best way seems to be using double sided tape, egally applied to the bottom PCB surface. Then the PCB is attached to the flattened (by milling) MDF surface. The tape will help in straighten the PCB surface by pulling it against the MDF surface.

Buy strong double sided tape (not very thick)

Make a flat bottom surface. Please notice that 'flat' is relative to the CNC machine & milling spindle (Dremel). So the best way to do this is placing the CNC router on a new MDF panel (18mm minimum) and mill about 1mm of the surface away. Then we are sure that the relative height/depth is the same for each possible coordinate. We need the following:

I loaded the same test shape that we used before for testing PCB milling

Some parts on the PCB are milled deep enough, others are not

This can be solved by milling a square in the MDF bottom plate, so that the whole surface is equal in depth related to the CNC machine

With the 15° 0.1mm bit we should be able to increase the depth easily

Edges are very smooth (best so far)

Extrusion moulding

A nice guide made by a guy who makes robotics components in his garage. He mills out the parts, makes a silicone mold and then casts the parts in PU. Buildlog: buildlog, part 1 and part 2 of the guide.

ToDo

replace the plastic guiding bearings with some better metal bearings. One of the plastic ones has the tendency to stay behind

make .g (the extension for gcode) an accepted extension on the wiki so we can upload it here.

Create an emergency stop button. While there is a stop button in replicatorG, this doesn't immediately stop the CNC, which will first execute some cached instructions.

while the endmill is less than 1mm, it's path seems to be about 2mm to the naked eye. This greatly decreases our accuracy.